Polyphenyl thioether lubricating compositions

ABSTRACT

LUBRICATING COMPOSITIONS COMPRISING POLYPHENYL THIOETHERS, POLYPHENYL ETHERS-THIOETHERS OF MIXTURES THEREOF AND CONTAINING SMALL AMOUNTS OF A POLAR ORGANIC COMPOUND AND AN ORGANIC PHOSPHINIC ACID OR ESTER HAVING IMPROVED LUBRICATING PROPERTIES. THESE COMPOSITIONS ARE USEFUL AS LUBRICATANTS OVER WIDE TEMPERATURE RANGES.

United States Patent 3,832,303 POLYPHENYL THIOETHER LUBRICATIN GCOMPOSITIONS Frank S. Clark, St. Louis, Mo., assignor to MonsantoCompany, St. Louis, M0.

N0 Drawing. Original application Dec. 30, 1970, Ser. No. 102,969, nowPatent No. 3,748,269, dated July 24, 1973. Divided and this applicationFeb. 5, 1973, Ser. No. 329,954

Int. Cl. Cm 1/48 US. Cl. 252-46.6 2 Claims ABSTRACT OF THE DISCLOSURELubricating compositions comprising polyphenyl thioethers, polyphenylethers-thioethers or mixtures thereof and containing small amounts of apolar organic compound and an organic phosphinic acid or ester haveimproved lubricating properties. These compositions are useful aslubricants over wide temperature ranges.

This is a division of application Ser. No. 102,969, filed Dec. 30, 1970,now US. Pat. No. 3,748,269, dated July 24, 1973.

This invention relates to improved lubricating compositions comprisingpolyphenyl thioethers, mixed polyphenyl ethers-thioethers and mixturesthereof, containing from 3 to 8 aromatic groups and a small amount of apolar organic compound and an organic phosphinic acid as lubricatingadditives.

Polyphenyl thioethers and polyphenyl ether-thioether combinations havefound wide application as functional fluids due to their excellentthermal stability and lubricity. For example they have been found to bevaluable as hydraulic fluids and as lubricants in motor operation,particularly in jet engines.

Development of synthetic base stocks such as the polyphenyl thioetherhas provided lubricant fluids which are useful at elevated temperaturesuch as 400 to 500 F. It is known that one of the aspects in which thepolyphenyl thioether base stocks are considered deficient is in theirlubricating characteristics, especially for steel on steel or on chromeanodized aluminum. These lubricating characteristics include theload-carrying abilities and wear properties, especially under conditionsof pumping the lubricant where the pump contains a chrome anodizedaluminum bearing surface or gear box. Thus there is a demand foradditives for polyphenyl thioethers which additives will improve thelubricity of the polyphenyl thioethers for steel on steel or on chromeanodized aluminum surfaces.

An object of the present invention is to provide for improvedlubricating compositions employing polyphenyl thioethers, polyphenylether-thioethers, or mixtures thereof as base stocks for applicationswhere at least one of the surfaces to be lubricated is chrome anodizedaluminum.

These and other objects will become evident upon consideration of thefollowing specification and examples.

It has now been found that compositions consisting essentially of amajor amount of a polyphenyl thioether base fluid having the formulawherein R is a phenyl group, an alkyl-substituted phenyl group whereinthe alkyl group contains 1 to 4 carbon atoms, an alkoxy-substitutedphenyl group wherein the alkoxy group contains 1 to 4 carbon atoms or ahalogenated phenyl group wherein the halogen is bromine, fluorine orchlorine, R is a phenylene group, an alkyl or alkoxy-substitutedphenylene group where the alkyl group contains 1 to 4 carbon atoms or ahalogenated phenylene Patented Aug. 27, 1974 group wherein the halogenis fluorine, bromine or chlorine, and Y is selected from oxygen andsulfur but at least one of the Ys is sulfur and n is an integer having avalue of from 1 to 6 and additive amount of a polar organic compound andan organic phosphine acid have unusual ability to lubricate steel onchrome anodized aluminum and steel on steel.

*The amount of the polar organic compound employed in the compositionsof this invention can range from 0.01 to about 0.5 percent by weight. Itis preferred to employ the polar organic compound in the compositions ofthis invention in amounts of from 0.04 to 0.15 percent by weightbasedupon the total composition.

The amount of the organic phosphinic acid or ester employed in thecompositions of this invention is from about 0.05 to about 1.0 percentby weight of the total composition. It is preferred to employ theorganic phosphinic acid or ester in the compositions of this inventionin amounts of from about 0.070 to about 0.2 percent by weight of thetotal composition.

The improvement in lubricity characteristics achieved by the addition ofa perfluoro dibasic acid as the polar organic compound and the organicphosphinic acid or ester to the polyphenyl thioether base fluid isparticularly unusual and surprising. Wear on a chrome anodized aluminumbearing surface is decreased at test temperatures of 200 F. whereas whenthe base fiuid is tested without the additive the lubricity of the basefluid is not sufficient and the bearing surface fails after a shorttime.

Thepolar organic compounds which are employed in the .compositions ofthis invention include aliphatic perfluor'o dibasic acids, carboxysubstituted polyphenyl thioesters, substituted phenols and arylsubstituted fatty acids, acetylene dicarboxylic acid, aryl phosphates,and the like.

Illustrative of aliphatic perfluoro dibasic acids which can be employedin the compositions of this invention are the perfiuorinated dibasicaliphatic acid containing from 3 to 1-0 carbon atoms and represented bythe formula wherein n is an integer of from 1 to 8. It is particularlypreferred to employ perfiuorinated dibasic acid of formula II wherein nis an integer of from 2 to 6.

Illustrative of the carboxy substituted polyphenyl thioethrs which areemployed in the compositions of this invention are those having theformula where in R, R, Y and n are as above-defined with the provisothat at least one Y is sulfur and that from one to two of -R and R issubstituted with a carboxy group and x is an integer of 1 or 2. Suchcarboxy substituted polyphenyl thioethers are for examplem-(m-phenylmercaptophenylmercapto)benzoic acid,m-(phenylmercapto)benzoic acid,o-(m-phenylmercaptophenylmercapto)benzoic acid and the other carboxysubstituted polyphenyl thioethers.

Illustrative of the substituted phenols which are useful in thecompositions of this invention are the 2,6-(alkyl) phenols such as forexample 2,6-di-t-butyl-4-methyl phenol and the like. It is preferredthat the alkyl groups on the phenol contain from 1 to 12 carbon atoms.

Illustrative of the aryl substituted fatty acids which are useful in thecompositions of this invention are those having the general formulawherein Ar is an aryl .group containing from 6 to 16 carbon atoms and ais an integer of form 8 to 24. Illustrative of these aryl substitutedfatty acids are, for example, phenyloctadecanoic acid, phenyloctanoicacid, tolyldodecanoic acid, xylyltertracosanoic acid and the like.

3 Illustrative of the acetylenic dibasic acids useful in thecompositions of this invention are those having the general formulawhere b and c are integers of from to inclusive. Acetylene dicarboxylicacid is especially preferred for use in the compositions of thisinvention. Illustrative of the aryl phosphate esters useful in thecompositions of this invention are those having the formula wherein R isan aryl group containing from 6 to 16 carbon atoms and R and R are alkylgroups containing from 1 to 1-2 carbon atoms or an R group. It ispreferred that when R R and R all represent aryl groups that at leastone of the aryl groups be an alkyl substituted aryl group. Illustrativeof the phosphate esters are for example, tricresyl phosphate, dibutylphenyl phosphate, cresyl diphenyl phosphate, xylyl dicresyl phosphate,cresyl dioctyl phosphate and the like.

Illustrative of the perfiuorinated dibasic acids represented by formulaII are, for example, perfluoro malonic acid, perfluoro succinic acid,perfluoro azelaic acid and perfiuoro sebacic acid.

The organic phosphinie acids or esters which are employed in thecompositions of this invention are those of the formula wherein R" is anaryl group containing from 6 to 16 carbon atoms, a halogenated arylgroup or an alkyl group containing from 1 to 12 carbon atoms, and R" ishydro gen or an R" group. Illustrative of the groups represented by Rand R' are, for example, phenyl, tolyl, xylyl, naphthyl,a-methyl-naphthyl and diphenyl, and such aryl groups substituted withhalogen or with alkyl groups containing up to 10 carbon atoms. Furtheralkyl substituted aryl groups are nonylphenyl, ethylphenyl, butylphenyl,t-butylphenyl and the like. Such halogen substituted aryl groups arep-chlorophenyl, o-bromophenyl, m-fluorophenyl, piodophenyl, chlorotolyl,bromoxylyl, chloronaphthyl, and the like. Illustrative of the alkylgroups represented by R" and R are, for example, methyl, ethyl, propyl,isobutyl, pentyl, t-butyl, hexyl, isooctyl, nonyl, decyl, dodecyl, andthe like. Such aryl phosphinic acids are, for example, phenylphosphinicacid, nonylphenylphosphinic acid, tolylphosphinic acid; xylylphosphinicacid, naphthylphosphinic acid, diphenylphosphinic acid and the like. Itis especially preferred to employ in the compositions of this inventioncompounds of formula III wherein R" is an aryl group and R' is hydrogen.

The polyphenyl thioethers employed in the composition of this inventionhave from 3 to 8 benzene rings and from 1 to 7 sulfur atoms with thesulfur atoms joining the benzene rings in chains as ether linkages.

By the term polyphenyl thioether as used herein is meant a compound orphysical mixture of compounds represented by formula I. The termincludes compounds wherein all of the Ys in formula I are sulfur. Theterm also includes those compounds which contain both oxygen and sulfurlinkages betwen the benzene rings.

The compositions of this invention contain a major amount of thepolyphenyl thioether base stock, i.e., at least 50 percent by weight ofthe total composition comprises a polyphenyl thioether. It is preferredthat at least 60 percent by weight of the composition be a polyphenylthioether base stock and even more preferred that at least percent byweight of the total composition comprise a polyphenyl thioether.

The compositions of this invention can also contain from 0.01 to 10percent by weight of the total composition of a dialkyl hydrogenphosphite extreme pressure additive. The dialkyl hydrogen phosphitesuseful are those wherein the alkyl groups contain from 1 to 12 carbonatoms. These alkyl groups are for example, methyl, ethyl, propyl,isopropyl, butyl, sec-butyl, t-butyl, hexyl, decyl, isodecyl, dodecyland the like.

Illustrative of the alkyl-substituents present in the phenyl andphenylene groups of the polyphenyl thioethers are for example, methyl,ethyl, propyl, butyl and the like. Illustrative of thealkoxy-substituents are, for example, methoxy, ethoxy, propoxy, butoxyand their isomers.

Illustrative of the polyphenyl thioethers which can be employed as basestocks for the compositions of this invention are thebis(phenylmercapto)benzenes. For example bis (m-phenylmercapto benzenebis (o-phenylmercapto benzene bis (p-phenylmercapto benzenebis(m-phenylmercaptophenyl) sulfide bis(o-phenylmercaptophenyl sulfidebis (p-phenylmercaptophenyl sulfide (m-phenylmercaptophenyl)o-phenylmercaptophenyl) sulfide p-phenylmercapto-m-phenylmercaptodiphenyl sulfide o-bis (o-phenylrnercaptophenylmercapto benzene p-bis(p-phenyhnercaptophenylmercapto benzene p-bis(o-phenylmercaptophenylmercapto benzene p-bis(m-phenylmercaptophenylmercapto benzene m-bis(p-phenylmercaptophenylmercapto benzene o-bis(p-phenylmercaptophenylmercapto) benzene and the like and mixturesthereof.

Illustrative of the mixed polyphenyl ether-thioether compounds which canbe employed as base stocks in the compositions of this invention are forexample,

o-phenylmercapto-m-phenoxy benzene p-phenylmercapto-o-phenoxy benzenem-phenoxy-p-phenylmercaptobenzene o-phenylmercapto-p-phenoxydiphenylsulfide o-phenylmercapto-m-phenoxydiphenyl sulfideo-phenoxy-m'-phenylmercaptodiphenyl sulfidem-phenoxy-p-phenylmercaptodiphenyl sulfideo-phenoxy-p'-phenylmercaptodiphenyl sulfidep-phenoxy-p-phenylmercaptodiphenyl sulfideo-phenoxy-o'-phenylmercaptodiphenyl sulfide o,o'-bis (phenylmercapto)diphenyl ether o-phenylmercapto-m-phenylmercaptodiphenyl ethero-phenylmercapto-p-phenylmercaptodiphenyl etherm-(m-phenylmercaptophenylmercapto) (m-phenoxyphenylmercapto)benzene [m-(m-phenylmercaptophenylmercapto phenyl] [m- (m-phenoxyphenylmercaptophenyl] sulfide 3- (m-phenylmercaptophenylmercapto) -3m-phenylmercaptophenoxy) diphenyl sulfide 3, 3 'glllais m-phenylmercaptophenylmercap to) diphenyl e er 3- (rn-phenylmercaptophenylmercapto 3(m-phenoxyphenoxy) diphenyl sulfide 4-(m-phenylmercaptophenylmercapto)-4'- (m-phenylmercaptophenoxy)diphenylether 3- (m-phenylmercaptophenylmercapto) -3(m-phenoxyphenylmercapto)diphenyl ether 4,4'-bis(m-phenylmercaptophenoxy) diphenyl sulfide4,4'-bis(m-phenoxyphenylmercapto)diphenyl sulfide 3-(m-phenoxyphenylmercapto) -3 (m-phenylmercaptophenoxy) diphenyl sulfide3,3'-bis(m-phenylmercaptophenoxy)diphenyl ether 4-(m-phenylmercaptophenylmercapto )-4'- (m-phenoxyphenoxy) diphenyl etherIn addition to the foregoing compounds, the phenyl and phenylene groupsof such compounds can contain substituents, such as alkyl of 1 to 4carbon atoms, alkoxy of 1 to 4 carbon atoms and halogen such aschlorine, bromine and fluorine. Examples of such compounds are asfollows:

4,4'-bis(m-tolylmercapto) diphenyl ether 3,3 '-bis (m-tolylmercaptodiphenyl ether 2,4-bis (m-tolylmercapto diphenyl ether 3,4-bis(m-tolylmercapto) diphenyl ether 3,3-bis (p-tolylmercapto)diphenyl ether'3,3-bis(xylylmercapto)diphenyl ether 4,4-bis(xylylmercapto) diphenylether 3,'4'-bis'(xylylmercapto)diphenyl ether 3,4'-bis(m-isopropylphenylmercapto) diphenyl ether3,3'-bis(m-isopropylphenylmercapto)diphenyl ether2,4'-bis(m-isopropylp'henylmercapto)diphenyl ether3,4-bis(p-tert-butylphenylmercapto) diphenyl ether4,4'-bis(p-tert-butylphenylmercapto)diphenyl ether3,3-bis-(p-tert-butylphenylmercapto)diphenyl ether3,3'-bis(2,4-di-tert-butylphenylmercapto)diphenyl ether3,3'-bis(3-chlorophenylmercapto)diphenyl ether4,4-bis(3-chlorophenylmercapto)diphenyl ether3,3'-bis(m-trifiuoromethylphenylmercapto)diphenyl ether4,4'-bis(m-trifiuoromethylphenylmercapto)diphenyl ether3,4'-bis(m-trifluoromethylphenylmercapto)diphenyl ether2,3-bis(m-trifiuoromethylphenylmercapto)diphenyl ether 3,3'-bis(p-trifluoromethylphenylmercapto) diphenyl ether3,3-bis(o-trifiuoromethy-lphenylmercapto)diphenyl ether3,3'-bis(m-methoxyphenylmercapto)diphenyl ether3,4'-bis(m-isopropoxyphenylmercapto diphenyl ether 3 ,4'-bis(tn-perfluorobutylphenylmercap to) diphenyl ether2-(m-tolyloxy)-2-phenylmercaptodiphenyl sulfideZ-(p-tolyloxy)-'3-phenylmercaptodiphenyl sulfide2'(o-tolyloxy)-4-phenylmercaptodiphenyl sulfide3*(m-tolyloxy)-3-phenylmercaptodiphenyl sulfide3-(m-tolyloxy)-4'-phenylmercaptodiphenyl sulfide4-(In-tolyloxy)-4'-phenylmercaptodiphenyl sulfide3-xylyloxy-4-phenylmercaptodiphenyl sulfide3-xylyloxy-3'-phenylmercaptodiphenyl sulfide3-phenoxy-3-l(m-toly1n1ercapto)diphenyl sulfide3-phenoxy-4-'(m-tolylmercapto)diphenyl sulfide2-phenoxy-3-(p-tolylmercapto) diphenyl sulfide3-phenoxy-4'-(m-isopropylphenylmercapto)diphenyl sulfide 3-phenoxy-3-(m-isopropylphenylmercapto diphenyl sulfide3-m-toloxy-3-(m-isopropylphenylmercapto)diphenyl sulfide4-(m-trifluoromethylphenoxy)-4'-phenylmercaptodiphenyl sulfide3-(m-trifluoromethylphenoxy)-4'-phenylmercaptodiphenyl sulfide 2-(m-trifiuoromethylphenoxy -3 '-phenylmercaptodiphenyl sulfide 3-(m-trifiuoromethylphenoxy -3 '-phenylmercaptodiphenyl sulfide3(p-chlorophenoxy) -3-phenylmercaptodiphenyl sufide 3(m-bromophenoxy)-4'-phenylmercaptodiphenyl sulfide bis [m-(m-chlorophenoxyphenyl] sulfide m-bis 3 (p-methylphenylmercapto phenoxy] benzene m-bis[3- (m-trifiuoromethylphenoxy) phenylmercapto] benzene m-bis [3-(m-bromophenoxy phenylmercapto] benzene 3 ,3'-bis[m-(p-methylphenylmercapto)phenoxy1diphenyl sulfide 6 3 ,4-bis [m-(p-methylphenylmercapto phenoxy] diphenyl sulfide 3 (p-xenyloxy) -3'-phenylmercapto diphenyl sulfide,

and the like and mixtures thereof. It is also contemplated within thescope of this invention to employ mixtures of polyphenylether-thioethers as base stocks.

The compositions of this invention are useful as lubricants underextreme conditions. The compositions are especially useful for steel onchrome anodized aluminum lubrication.

The following examples serve to further illustrate the invention. Allparts are parts by weight unless otherwise expressly set forth.

EXAMPLE 1 A polyphenyl thioether-polyphenyl ether-thioether lubricantcomposition is prepared by combining perfiuoro glutaric acid (0.1 gram)and phenylphosphinic acid (0.075 gram) with 100 grams of a thioether ofthe following composition:

Percent by weight Meta-bis (phenylmercapto) benzene 50 Bis(phenoxyphenylsulfide 12 .5

(Phenoxyphenyl) (phenylmercaptophenyl) sulfide 23.5Bis(phenylmercaptophenyl)sulfide 12.65 3 ring and 5 ring thioethers 1.35

This mixture is stirred for about 12 hours at 40-45 C. After cooling toroom temperature the mixture is filtered to remove a small amount ofinsoluble material.

The aluminum lubricity of the composition of 'Example 1 was shown usinga chrome anodized oil pump. This is a Pratt & Whitney JT3D-3B mainengine pump. This type of pump is commonly used in jet engine gearboxes. The gear box oil pump is a compound pump composed of the pressureoil pump and the gear box scavenge pump operating from a single shaft.Both drive gears of the pumps and the rotating shaft are hung from twooutboard journals with a journal in the middle separating the two pumps.Rotating drive for both pumps is provided by a single axially locatedsplined shaft which extends through one side of the pump housing to apower source. The driven or idle mating gears in these pumps rotate on afixed shaft. The rotating shaft is steel, the case and journals arechrome anodized aluminum. Design loading is 50 p.s.i. for the pressurepump.

Normally, the journals are part of the pump case. For testing purposes,the housing is widened and chrome anodized bushings are placed betweenthe shaft and the journal. Lubricity failure results from wear orseizure of the bushings. These are then replaced allowing continualtesting with one pump.

A shock cycle test was used to evaluate fluids. The oil was circulatedin the pump under no load while being heated to 200 The output of thepump was throttled until a discharge pressure of p.s.i. was reached.This pressure was held for ten seconds, then lowered to zero p.s.i. forfive seconds. This elf-on shock cycle was repeated twenty times at 20p.s.i., twenty times at p.s.i., p.s.i., p.s.i., p.s.i., and p.s.i. Thisfinal load is 50 percent excess load above the design load. Completionof cycles Without Wear or seizure of the bushings constitutes asuccessful test.

The composition of Example 1 was able to complete 120 testing cycleswithout failure of the bushings. The base oil containing 0.1 percentdiisopropyl hydrogen phosphite failed the test after 60 cycles. The baseoil with only phenylphosphinic acid (0.1 percent) failed at 62 cycles.The thioethers containing only perfiuoroglutaric acid (0.08 percent)failed after 84 cycles.

The lubricating ability of the fluids of this invention was shown with aslow speed four ball machine. A slow speed four ball machine measuresthe boundary lubricity action of additives. This test is a variation ofthe well 7 known Shell Four Ball Test in which a ball is rotated againstthree stationary balls. Wear scars and/or seizure loads measure additivelubricity. In the slow speed instru ment the three stationary balls arereplaced with circular discs. Standard operating conditions are:

3 kg. load 1 r.p.m. Room temperature to 700 F.

The speed of rotation is very low, namely one r.p.m. This equals 0.88inches/minute. This is done for two reasons. It insures boundaryconditions, i.e., metal to metal contact. It also eliminates metal skintemperature flashes which can occur at high speeds. Thus the bulk oiltemperature is equivalent to the metal surface temperature. Under theseconditions wear is negligible and fraction is used to followlubrication. After covering the ball and disc with the test oil, theinitial friction is recorded. The test sample is then heated to 700 F.with continuous recording of the friction. This gives a boundaryfrictiontemperature profile for the experimental fluid over thistemperature range.

From 200 to 700 F. the boundary friction on M50 steel for the blend fromExample 1 was lower than that of the base stock containing only phenylphosphinic acid. The friction lowering was greatest above 600 F. Thistemperature range corresponds to the metal skin temperature of bearingcomponents at high temperature conditions.

EXAMPLE 2 To 100 grams of the base fluid of thioethers from Example 1was added 0.075 gram phenylphosphinic acid and 0.05 gram of acetylenedicarboxylic acid. After heating at 45 C. for about twenty hours, theblend was cooled to room temperature and filtered.

A boundary friction-temperature curve for the fluid from Example 2 wasrun on M50 steel. The boundary friction for the blend was significantlylowered relative to the base stock containing only phenylphosphinic acidover a temperature range of 400 to 700 F.

EXAMPLE 3 To 100 grams of the base fluid of the thioethers as set forthin Example 1 was added 0.075 gram phenylphosphinic acid and 0.05 gram ofm-(m-phenylmercaptophenylmercapto)benzoid acid. After heating at 45 forabout twenty hours, the blend Was cooled to room temperature andfiltered.

A boundary friction-temperature curve for the fluid from Example 3 wasrun on M50 steel. The boundary friction for the blend from 500 to 700 F.was significantly lower than a blend containing only phenylphosphinicacid.

EXAMPLE 4 To 100 grams of the base fluid of thioethers from Example 1was added 0.075 gram phenylphosphinic acid and 0.05 gram of2,6-di-t-butyl-4-methyl phenol. After heating at 45 C. for about threehours the blend was cooled to room temperature and filtered.

A boundary friction-temperature curve for the fluid from Example 4 wasrun on M50 steel. The boundary friction for the blend was eithersignificantly lower than, or equal to the boundary friction of the basestock containing only phenylphosphinic acid over a temperature range offrom room temperature to 700 F. From 500 F. to 700 F. the boundaryfriction of the blend of Example 4 was significantly lower than that ofthe blend containing only phenylphosphinic acid.

EXAMPLE 5 To 100 grams of the base fluid of thioethers from Example 1was added 0.075 gram phenylphosphinic acid and 0.05 gram oftricresylphosphate. After heating at 40 to 45 C. for about 3 hours theblend was cooled to room temperature and filtered.

A boundary friction-temperature curve for the fluid from Example 5 wasrun on M50 steel. The boundary friction for the blend was lower than fora base stock containing only the phenylphosphinic acid over atemperature range of from room temperature to 700 F.

EXAM PIE 6 To grams of the base fluid of thioethers from Example 1 wasadded 0.075 gram phenylphosphinic acid and 0.05 gram ofphenyloctadecanoic. After heating at 40 to 45 C. for bout 3 hours theblend was cooled to room temperature.

A boundary friction-temperature curve for the fluid from Example 6 Wasrun on M50 steel. The boundary friction for the blend was lower than fora base stock containing only the phenylphosphinic acid over atemperature range of from 600 to 700 F.

It will be appreciated that the composition of the invention, inaddition to the polyphenyl thioether base fluid and the organicphosphinic acid additive, may also contain other additives, such asoxidation inhibitors, rust and corrosion inhibitors, antifoaming agents,detergents, viscosity index improvers such as polymeric materials forexample, polyacrylate alkyl esters, polymethacrylate alkyl esters,polyoxyalkylene compounds, polyurethanes and the like. Such additivesare usually employed in amounts as low as 10 parts per million forantifoaming agent to as much as 15 parts by weight of the totalcompositions for viscosity index improvers.

While this invention has been described with respect to various specificexamples and embodiments, it is understood that the invention is notlimited thereto and that it can be variously practiced within the scopeof the following claims.

The embodiments of this invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A lubricant composition consisting essentially of a major amount of apolyphenyl thioether having the formula wherein R is a phenyl group or asubstituted phenyl group, R is a phenylene group or substitutedphenylene group, in which the substituents on said phenyl and phenylenegroups are halogen, alkyl or alkoxy containing from 1 to 4 carbon atoms,n is an integer of from 1 to 6, Y is sulfur or oxygen provided that atleast one of the groups represented by Y is sulfur, and mixtures of suchthioethers and from about 0.05 to about 1.0 percent by weight of anorganic phosphinic acid of the formula wherein R" is an aryl group offrom 6 to 16 carbon atoms, a halogen substituted aryl group of from 6 to16 carbon atoms, an alkyl substituted aryl group containing from 6 to 16carbon atoms or an alkyl group containing 1 to 12 carbon atoms, R' ishydrogen or an R" group and from 0.01 to 0.5 percent by weight ofcarboxy substituted polyphenyl thioethers having the formula wherein -R,R, Y and n are as above-defined with the proviso that at least one Y issulfur and that fromone to two of R and R is substituted with a carboxygroup and x is an integer of 1 or 2.

' 2. A composition of Claim 1 wherein the carboxy substituted polyphenylthioether is m(m-phenylmercaptophenyl)benzoic acid.

References Cited UNITED STATES PATENTS 3/1967 Campbell et al 25245 X 12,274,291 2/1942 Clayt n et al. 25249.8 2,730,499 1/ 1956 Pokorny25249.8 2,318,629 5/ 1943 Prutton 25248.6 X

FOREIGN PATENTS 851,651 10/ 1960 Great \Britain 25252 R WARREN H.CANNON, Primary Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION I atent No.3,832,303 Dated August 27, 1974 Inventgnfg) Frank S. Clark I It iscertified that error appears in the above identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 2, line 4, should be "and an additive amount Column 2, line 5,"phosphine" should be phosphinic Column 2, line 72,"xylyltertrac0sanoic" should be ylyltetracosanoic Column 3, formulaonline 4, reads Signed and sealed this 18th day of February 1975. Column7, line l7, "fraction! should be friction ol 7 line 48 "benzoid" shouldbe benzoic s2: i Attest:

' C. MARSHALL DANN RUTH C. MASON I Commissioner of Patents ArrestingOfficer and Trademarks

